Abstract : Silicone elastomer is widely used as the material of choice for fabricating maxillofacial prosthesis. However, silicone properties are far from ideal; low tear strength, low tensile strength and insufficient elasticity are the most undesirable properties. The purpose of this study was to evaluate the effect of addition of nano SiO2filler on tear strength, tensile strength, elongation at break, hardness and color of Cosmesil M-511 HTV maxillofacial silicone elastomer. Nano SiO2was added to the silicone base in concentrations of 4%, 5% and 6% by weight. Silicone with 0% nano filler served as a control. Tear test was done according to ISO 34-1. Tensile and elongation test was done according to ISO 37. Shore A hardness test was done according to ISO 7619. Visual color measurement test was done according to ASTM D1535. Scanning electron microscope was used to assess the efficiency of dispersing method. FTIR test was conducted to evaluate the interaction of nano SiO2with the silicone. Statistical analysis was done using one-way ANOVA and Fisher’s LSD test. SEM showed well dispersion of nano filler within the silicone matrix. FTIR indicated that nano SiO2interacted with the PDMS through its surface hydroxyl group. All nano SiO2concentration groups showed a highly significant increase in tear strength, tensile strength and elongation at break compared to the control group. The 5% group showed the highest mean values among other groups. Shore A hardness showed a highly significant increase with all nano SiO2concentrations with the increase being directly proportional to filler concentration increase. Spectrophotometer results showed a highly significant decrease in translucency of the material with all nano filler concentrations but this decrease in translucency was visually demonstrated as slight increase in color intensity. Reinforcement of M-511 silicone with 5% nano SiO2significantly improves all mechanical properties tested with a slight change of color seen visually.
The most used material in the world after water is concrete, which depends mainly on its manufacture of cement leading to the emission of carbon dioxide (CO2), flying dust, and other greenhouse gasses (GHGs) resulting in pollution of the atmosphere. The emission of CO2 from cement production is approximately 5% of the global anthropogenic CO2. This research focuses on investigating the amount of CO2 emission from the Iraqi General Cement Company plants includes the cement factories of Kirkuk, Al-Qa’em, Fallujah, and Kubaisa, using the GHGs Protocol Measures Program (specifically cement based-method).
This study describe the effect of temperature on the optical
properties of nickel(ii) phthalocyanine tetrasulfonic acid tetrasodium
salt (NiPcTs) organic thin films which are prepared by spin coating
on indium tin oxide (ITO-glass). The optical absorption spectra of
these thin films are measured. Present studies reveal that the optical
band gap energies of NiPcTs thin films are dependent on the
annealing temperatures. The optical band gap decreases with increase
in annealing temperature, then increased when the temperature rising
to 473K. To enhance the results of Uv-Vis measurements and get
more accurate values of optical energy gaps; the Photoluminescence
spectra of as-deposited and annealed NiPcTs thin fi
Polycrystalline Cadmium Oxide (CdO) thin films were prepared using pulsed laser deposition onto glass substrates at room temperature with different thicknesses of (300, 350 and 400)nm, these films were irradiated with cesium-137(Cs-137) radiation. The thickness and irradiation effects on structural and optical properties were studied. It is observed by XRD results that films are polycrystalline before and after irradiation, with cubic structure and show preferential growth along (111) and (200) directions. The crystallite sizes increases with increasing of thickness, and decreases with gamma radiation, which are found to be within the range (23.84-4.52) nm and (41.44-4.974)nm before and after irradiation for thickness 350nm and 4
... Show MoreThe electronic properties (such as energy gap HOMO levels. LUMO levels, density of state and density of bonds in addition to spectroscopic properties like IR spectra, Raman spectra, force constant and reduced masses as a function of frequency) of coronene C24 and reduced graphene oxide C24OX , where x=1-5, were studied.. The methodology employed was Density Functional Theory (DFT) with Hybrid function B3LYP and 6-311G** basis sets. The energy gap was calculated for C24 to be 3.5 eV and for C24Ox was from 0.89 to 1.6862 eV for x=1-5 ,respectively. These energy gaps values are comparable to the measured gap of Graphene (1-2.2 eV). The spectroscopic properties were compared with experimental measurements, specificall
... Show MorePolycrystalline Cadmium Oxide (CdO) thin films were prepared
using pulsed laser deposition onto glass substrates at room
temperature with different thicknesses of (300, 350 and 400)nm,
these films were irradiated with cesium-137(Cs-137) radiation. The
thickness and irradiation effects on structural and optical properties
were studied. It is observed by XRD results that films are
polycrystalline before and after irradiation, with cubic structure and
show preferential growth along (111) and (200) directions. The
crystallite sizes increases with increasing of thickness, and decreases
with gamma radiation, which are found to be within the range
(23.84-4.52) nm and (41.44-4.974)nm before and after irradiation for
Background: Recently, Poly propylene fibers with and without plasma treatment have been used to reinforce heat cure denture base acrylic but, so far some of properties like tensile strength , wettability and wear resistance not evaluated yet, the aim of the study is to clarify the influence of incorporation of treated and untreated fibers on these properties. Materials and methods: Twenty one specimens were fabricated for every tested property(tensile strength, wear resistance and wettability) that classified into three groups(control, untreated poly propylene fibers reinforced specimens and Oxygen plasma treated group)and for each test sevens amples were used(n=7). Tensile strength was tested using Instron universal testing machine, wear
... Show MoreABSRTACT Background: Soft liner material is become important in dental prosthetic treatment. They are applied to the surface of the dentures to achieve more equal force distribution , reduce localized pressure and improve denture retention by engaging undercut . So the aim of the study is to evaluate the effect of different surface treatment by air-abrasion AL2O3 and laser treatment with CO2 laser on improving the shear bond strength of the denture liner to acrylic denture base material . Materials and methods: the 30 specimens of heat cured acrylic denture base material (high Impact acrylic )and heat cured soft liner (Vertex ,Nether Lands )were prepared for this study .They were designed and divided according to type of the s
... Show MoreThe problem of steady, laminar, natural convective flow in an square enclosure with and without partitions is considered for Rayleigh number (103-106) and Prandtl number (0.7). Vertical walls were maintained isothermal at different temperatures while horizontal walls and the partitions were insulated. The length of partition was taken constant. The number of partitions were placed on horizontal surface in staggered arrangement from (1– 3) and ratio of partition thickness (H/L= 0.033, 0.083, 0.124). The problem is formulated in terms of the vorticity-stream function procedure. A numerical solution based on a program in Fortran 90 with the finite difference method is obtained. Representative results illustrating the effects of the thickn
... Show MoreBackground: In this study we evaluate the effect of plasma treatment (oxygen and argon) gas in two different exposure times on the surface of heat cure and light cure acrylic resin. Materials and method: 100 specimens of heat cure and light cure acrylic resin were fabricated. The measurements of the samples were (75mm, 25mm and 4.5mm) length, width and depth respectively with stopper of 3mm depth. Two types of gas used oxygen and argon in (5,10) min by using (DC-glow discharge plasma device) then we apply cold cure soft lining material, with the help of Instron machine we test the shear stress value. Results: A highly significant effect after argon and oxygen gases treatment in both 5 and 10 min exposure times on shear bond strength to soft
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